Feasibility of Using Permeable Block Sabo Dams Incorporating Breakwater Structures for Volcanic Sediment Management

Since the Edo Era, debris flows have been analogously called “mountain tsunamis”, implying that strategies historically used to mitigate tsunamis in coastal regions in Japan could provide insightful points of reference for debris flow management. The recent use of secondary product blocks and terracing for sediment control has seen nationwide acceptance, including their impending implementation in sabo dams and diversion levees for volcanic sediment control. Volcanic sediment control includes measures that manage pyroclastic flows during eruptions and general methods that counter ashfall mudslides triggered by rain. Therefore, deploying these block-centric measures within volcanic regions requires their stability against external disturbances such as debris flows, and their trapping functionality must be maintained on mutable ground. In this study, we introduce novel sabo dams that combine conventional block sabo dams with breakwater structures that are typically deployed in coastal zones. We examined their stability during debris flow interception in basic experiments, and explored their flexural capacity and extent of deformation on mutable ground in analogous rudimentary experiments. We propose a sabo dam configuration that incorporates breakwater structures for maintaining stability against disturbances such as debris flows. Our results suggest the potential efficacy of the interlocking permeable block design for augmenting the flexural resilience of a block sabo dam on mutable ground. A novel phenomenon, the interlocking-beam effect, could potentially bolster displacement resistance.